After building my full size Wall-E, I thought I was finished building anything even remotely robotics-related. I had spent a little over 2.5 years working on him, and I really needed a break. Of course, I ended up inspired by Matt Hobbs’ remote-controlled pit droid kart, and I decided that I needed to tackle building one of my own.
I reached out to a fellow builder here in Georgia who had built a very cool remote controlled Chuckie driving a tricycle. He told me that he mixed elements from the instructables here:
https://www.instructables.com/The-Bike-Riding-Skeleton/
https://www.instructables.com/Remote-Controlled-Tricycle-Riding-Puppet
These didn’t seem too complicated, so I pulled the trigger on the base frame of the kart. It’s a pedal-powered kart by Berg. I picked up a similar one on Amazon. https://amzn.to/4bUXLHO
While I was waiting for the kart to arrive, I got to work printing out my pit droid. I bought my files at Droid Division over on etsy.
https://www.etsy.com/listing/738096855/spacebobs-pit-droid-inspired-movie
The files are well worth the money and include updates and bonus files. They print very well and assemble without any issue.
Once my kart arrived, I had to put my printed pit droid onto it just to see what it would eventually look like. Even though the pit droid was not completely assembled, I was not disappointed!
The first thing I needed to purchase for the conversion was a 12v motor. This is the one I went with. https://amzn.to/4hie5nh
I soon realized that I needed to have some way to mount the motor to the frame. I wanted to put the motor somewhere in this area.
I created two brackets in Fusion 360. One bracket has a center hole for the motor shaft and three additional holes for screws to attach the motor to the bracket. The other bracket functions as a support structure. I printed out these templates to verify if my design would work or not. This is what they looked like:
I discovered that I would need to make the main bracket longer to be able to move the motor out to meet the sprocket on the axle. And the support bracket needed an opening that would allow the wires to pass through when mounting it. Once I finalized the design, I sent it off to sendcutsend.com to make my metal parts.
Next, I had to find a sprocket for the axle. The sprocket I ended up picking up is Roller Chain Sprocket For Ansi 25 Chain, 45 Teeth, For 7/8″ Shaft Diameter 2737T314. The chain for the motor and axle was found over on Amazon.
Once the metal brackets arrived, I went to work bending the main bracket to fit. That was quite a bit of trial and error to get right! Once I was happy with the shape, I welded both brackets to the frame of the kart.
I added the large sprocket to the axle and tested the motor out. I was thrilled with how well it worked!
With the main motor now tackled, I went to work on the steering. I picked up two linear actuators to control the left and right steering. These were mounted to the front underside of the kart using the brackets that come with the servos. These are attached to the frame with pop rivets. I secured the arms of the servos together with a long pivot screw, made using some metal spacers. I had to drill into the steel arm of the steering mechanism to mount the pivot point. These servos work together in the transmitter, so when one pulls, the other pushes in equal amount.
In the video below, you can see how everything looks when tested out all together. I am using a Syren 10 board to control the motor. I’m pretty happy with the result so far!
Next up will be designing a metal frame to hold all of the electronic components and battery. Stay tuned!
